1. Field of the Invention
The present invention relates to a novel naphthalene derivative, useful as a dye or pigment or an intermediate thereof. The present invention also relates to a hair dye composition containing the novel naphthalene derivative, which is capable of dyeing hair with good color fastness.
2. Description of the Related Art
Conventional vat dyes for use in dyeing fibers are those which are first converted, with reducing agents, to the colorless leuco states in dyeing baths and then air oxidized in the baths, while dipping fibers therein, to insoluble colored states adsorbed on the dipped fibers. For example, indigo, a known and typical vat dye, has the following chemical structure (II): ##STR2## when indigo is used in dyeing, the fibers to be dyed are dipped in a dyeing solution containing the indigo, an alkaline compound, and a reducing compound. The indigo is in the leuco state having the following formula (III) under these conditions. ##STR3##
In addition to indigo, other dyes such as indanthrene dyes and anthraquinone dyes are also known as vat dyes. These dyes are also used to color or dye fabrics by a mechanism similar to that mentioned above.
The above-mentioned leuco states are very unstable and are immediately oxidized upon contact with air. Accordingly, it is necessary, in practice, to incorporate a large amount of a reducing agent in a dyeing bath. This incorporation, however, produces severe conditions in the fibers to be dyed. Furthermore, the reduction of indigo under alkaline conditions causes damage to the fibers.
It is well-known in the art that, although Helindon Yellow R developed by Cassella Co., comprised of naphthoquinone dyes having a condensed carbazole ring are yellow vat dyes suitable for dyeing wool, it has not been placed on the market because of the disadvantage that a strong alkaline bath is required in the reduction step. Use of the sulfuric acid ester of indigo in the leuco state has been proposed. However, since sulfuric acid ester is too stable, it is impossible to obtain the desired color unless a strong oxidizing agent such as potassium permanganate is used. The use of such a strong oxidizing agent also is likely to cause damage to the fibers. In addition, the improvements in the coloring power of conventional vat dyes are desired in the art because this coloring power is still unsatisfactory.
On the other hand, dye components used mainly in conventional hair dyes are oxidation dyes, which are capable of dyeing or coloring hair by oxidatively polymerizing, for example, a developer such as p-phenylenediamine, p-tolylenediamine, or other benzene derivative, and a coupler such as resorcinol, m-aminophenol, or m-phenylenediamine in the presence of hydrogen peroxide and ammonia. Similarly, it is known in the art as described in, for example, German Pat. No. 3016905, that oxidation dyes composed of indole and pyrimidine derivatives having dyeing mechanisms similar to the above-mentioned oxidation dyes are used in hair dyes.
Furthermore, various hair dyes containing, as a dye component, quinone type coloring agents have been proposed in, for example, German Offenlegungsschrift Nos. 3244452 and 3244454 and French Pat. No. 1567219. However, these coloring agents are used as a direct dye for dyeing hair but are used only to provide a certain shade to the air, e.g., tinting or color rinsing.
It has also been reported that botanical extracts, for example, certain extracted components derived from henna are used or dyeing hair. However, the coloring power of these extracts still not as satisfactory as desired.
Although the above-mentioned oxidation dyes are capable of imparting a good dyeing action to hair, the reactions involved in the course of the dyeing are extremely complicated and produce various kinds of oxidation products, since the coloring occurs through the above-mentioned oxidative polymerization. For this reason, it may often occur that the resultant color is remarkably varied, depending upon very slight differences in the dyeing conditions, even when the same dye is used. In addition, since these dyes are very unstable in air or in solvents (e.g., these dyes are susceptible to oxidation or oxidative polymerization), care must be taken during the handling thereof. For example, these dyes should be stored under an oxygen free atmosphere, for example, a nitrogen atmosphere. Furthermore, these dyes sometimes cause damage to the skin or hair when applied, depending upon individual reactions to the dye. Therefore, there is a strong need in the art for the development of new types of hair dyes which have a satisfactory coloring power, good color stability when applied, good storage stability, and a high safety level.